News & Articles

Can Ultrasound Read Your Mind?

Mark V. Kingsley

Short answer: Yes, it can. Long Answer: In the 1980s, neuroscientist Benjamin Libet conducted a controversial study that found a half-second delay when measuring the time between when subjects felt they had made a conscious decision to flick their wrists and the corresponding neural activity in the brain. The neural activity in question here was Bereitschaftpotential, the build-up of an electrical signal in the brain corresponding to voluntary muscle movement (and a fun word to try to say aloud). Since Libet was able to predict movement before the subject reported being aware of the decision, the study made waves due to the implications for the nature of free will

Of course, that study has been criticized heavily by neuroscientists and philosophers – for different reasons, but ultimately because “proving” anything conclusive about a concept like free will is problematic in both fields. However, the study is relevant here because it is one example of a crude brain-machine interface (BMI) being used to interpret neural activity. A more recent study reported on by the website Technology Networks uses a far more sophisticated BMI assisted by machine learning algorithms and, of note, functional ultrasound. These two technologies were used to map the neural activity of non-human primates to accurately predict the timing and direction of movement. While Libet’s experiment may not have “disproven” free will, it did foreshadow how the tools neuroscientists use could expand to study the mechanisms behind behavior. And the developments in functional ultrasound may just be the key to making what sounds like science fiction into a standard experiment.

Technically, reading minds (or, more accurately, mapping out brains through neural activity) has been a thing for a while. The difficulty for neuroscientists in creating an effective BMI is that it typically requires invasive procedures to be effective. For instance, brain surgery to physically implant electrodes in the brain (electrophysiology). Electroencephalography (EEGS) eschew surgery but cannot measure neural activity with high spatial resolution. Lastly, using an MRI as a BMI requires bulky and expensive equipment.

Ultrasound, however, can “hear” red blood cells in the brain through the corresponding pitch that results from their movement. Neuroscientists now understand that an increase in blood flow in a particular area of the brain correlates with an increase in neural activity there. And now, such activity can be mapped out by functional ultrasound technology. In the more recent experiment, machine learning algorithms were used to recognize patterns of activity that could then be interpreted and used as predictions. And, simple as that, ultrasound can read minds just by “listening” to what is happening in the brain before certain movements occur. While this is no reason to suspect we will be living in a Minority Report type of society any time soon, it is a fascinating application of functional ultrasound, a tool proving to be revolutionary in imaging, diagnostics, and now experimentation.

April 8, 2021 Newsletter